自由支撑GaN基LED薄膜发光性能的研究
发布时间：2018-09-10 09:45
【摘要】：目前硅衬底Ga N基LED外延薄膜缓减张应力和防止裂纹的方法主要有两种:其一为使用图形硅衬底,其二为生长较厚的铝镓氮缓冲层,这两种方法各有优缺点。尽管图形硅衬底Ga N基LED已经实现批量生产并逐渐为市场所接受,然而它还有大量的科学技术问题有待解决,诸多研究空白值得进行深入研究。其中,研究清楚单个图形内不同微区的发光性能及应力状态、衬底和缓冲层与量子阱层的应力交互作用及其对发光性能的影响等问题,对于提高硅衬底Ga N外延薄膜质量和器件性能具有重要指导意义,因此本文系统研究了图形硅衬底Ga N基LED薄膜去除衬底及Al N缓冲层后单个图形内微区发光及应力变化。光致发光谱是研究Ga N基LED的一种重要研究手段,然而硅衬底是不透光衬底,它对可见光具有一定的反射率,在硅衬底上外延的LED薄膜其光致发光谱会存在明显的干涉现象,这给准确的研究硅衬底LED的发光性能带来极大困难。本文,利用Ga N特有的特性,研究了一种获得无干涉的硅衬底LED薄膜PL谱的测试方法,为准确的研究硅衬底Ga N基薄膜发光性能带来极大便利。本文的主要研究内容和结论如下:1、去除图形硅衬底后,自由支撑的LED薄膜朝衬底方向呈柱面弯曲状态,且相邻图形的柱面弯曲方向不一致,当进一步去除Al N缓冲层后薄膜会由弯曲变为平整。2、LED薄膜在去除硅衬底前后同一图形内不同位置的PL谱具有显著差异,而当去除氮化铝缓冲层后不同位置的PL谱会基本趋于一致.3、LED薄膜每一位置的PL谱在去除硅衬底后均出现明显红移,进一步去除AlN缓冲层后PL谱出现程度不一的微小蓝移.4、自由支撑的LED薄膜去除氮化铝缓冲层后PL光强随激光激发密度变化的发光强度光衰减(Droop)得到改善。5、在PL谱的探测光路上采用经湿法粗化的GaN薄膜作为消干片,能基本彻底消除硅衬底Ga N基薄膜PL谱中的明显干涉现象,该方法消干效果好于目前文已报道的Ga N薄膜光谱的消干方法。
[Abstract]:At present, there are two main methods to reduce tensile stress and prevent cracks in Ga N-substrate LED epitaxial thin films on silicon substrate. One is to use patterned silicon substrate, the other is to grow thick aluminum-gallium nitrogen buffer layer. These two methods have their own advantages and disadvantages. Although the graphic silicon substrate Ga N-base LED has realized batch production and has gradually been accepted by the market, it still has a large number of scientific and technological problems to be solved, and many research gaps are worthy of further study. Among them, the luminescence properties and stress states of different microregions in a single figure, the stress interaction between substrate and buffer layer and quantum well layer, and their effects on luminescence performance are studied. It is important to improve the quality and device performance of Ga N epitaxial films on Si substrates. Therefore, the luminescence and stress changes in a single image microregion after the removal of substrate and Al N buffer layer from Ga N based LED films on graphically silicon substrates have been systematically studied in this paper. Photoluminescence spectroscopy is an important method to study Ga N-base LED. However, silicon substrate is an impervious substrate, which has a certain reflectivity to visible light. The photoluminescence spectra of LED films epitaxial on silicon substrates have obvious interference phenomenon. This makes it very difficult to accurately study the luminescent properties of Si substrate LED. In this paper, using the characteristic of Ga N, a method of obtaining PL spectra of LED films on Si substrates without interference is studied, which brings great convenience to the accurate study of the luminescence properties of Ga N-base films on Si substrates. The main contents and conclusions of this paper are as follows: 1. After removing the patterned silicon substrate, the free-supported LED film is cylindrical bending towards the substrate, and the cylindrical bending direction of the adjacent figure is not consistent. When the buffer layer of Al N is removed further, the film will change from bending to leveling. The PL spectra of different positions in the same figure before and after the removal of silicon substrate have significant differences. When aluminum nitride buffer layer is removed, the PL spectra at different positions tend to be consistent. The PL spectra of each position of the thin film tend to red shift obviously after the removal of silicon substrate. After further removing the AlN buffer layer, the PL spectrum appears a little blue shift of varying degrees. 4. After the free supported LED film removes the aluminum nitride buffer layer, the luminescence intensity attenuation (Droop) of PL with the laser excitation density is improved. 5. In the PL spectrum, the light intensity attenuation (Droop) of the PL light intensity changes with the laser excitation density is improved. Using GaN thin film coarsened by wet process as a dry elimination chip, The obvious interference phenomenon in the PL spectrum of Ga N based films on silicon substrate can be eliminated completely. This method is better than the previous reported method in eliminating the dry spectrum of Ga N thin films.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.2;TN312.8
本文编号：2234088
[Abstract]:At present, there are two main methods to reduce tensile stress and prevent cracks in Ga N-substrate LED epitaxial thin films on silicon substrate. One is to use patterned silicon substrate, the other is to grow thick aluminum-gallium nitrogen buffer layer. These two methods have their own advantages and disadvantages. Although the graphic silicon substrate Ga N-base LED has realized batch production and has gradually been accepted by the market, it still has a large number of scientific and technological problems to be solved, and many research gaps are worthy of further study. Among them, the luminescence properties and stress states of different microregions in a single figure, the stress interaction between substrate and buffer layer and quantum well layer, and their effects on luminescence performance are studied. It is important to improve the quality and device performance of Ga N epitaxial films on Si substrates. Therefore, the luminescence and stress changes in a single image microregion after the removal of substrate and Al N buffer layer from Ga N based LED films on graphically silicon substrates have been systematically studied in this paper. Photoluminescence spectroscopy is an important method to study Ga N-base LED. However, silicon substrate is an impervious substrate, which has a certain reflectivity to visible light. The photoluminescence spectra of LED films epitaxial on silicon substrates have obvious interference phenomenon. This makes it very difficult to accurately study the luminescent properties of Si substrate LED. In this paper, using the characteristic of Ga N, a method of obtaining PL spectra of LED films on Si substrates without interference is studied, which brings great convenience to the accurate study of the luminescence properties of Ga N-base films on Si substrates. The main contents and conclusions of this paper are as follows: 1. After removing the patterned silicon substrate, the free-supported LED film is cylindrical bending towards the substrate, and the cylindrical bending direction of the adjacent figure is not consistent. When the buffer layer of Al N is removed further, the film will change from bending to leveling. The PL spectra of different positions in the same figure before and after the removal of silicon substrate have significant differences. When aluminum nitride buffer layer is removed, the PL spectra at different positions tend to be consistent. The PL spectra of each position of the thin film tend to red shift obviously after the removal of silicon substrate. After further removing the AlN buffer layer, the PL spectrum appears a little blue shift of varying degrees. 4. After the free supported LED film removes the aluminum nitride buffer layer, the luminescence intensity attenuation (Droop) of PL with the laser excitation density is improved. 5. In the PL spectrum, the light intensity attenuation (Droop) of the PL light intensity changes with the laser excitation density is improved. Using GaN thin film coarsened by wet process as a dry elimination chip, The obvious interference phenomenon in the PL spectrum of Ga N based films on silicon substrate can be eliminated completely. This method is better than the previous reported method in eliminating the dry spectrum of Ga N thin films.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.2;TN312.8
【参考文献】
相关期刊论文 前1条
1 李述体,王立,辛勇,彭学新,熊传兵,姚冬敏,江风益;MOCVD生长的GaN单晶膜的蓝带发光研究[J];发光学报;2000年01期
，本文编号：2234088
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